The objective of this proposal is to develop a clearer understanding of the underlying mechanisms of the autoimmune disease, experimental allergic encephalomyelitis (EAE). EAE is used as a model with the hope that the knowledge gained can be applied to other autoimmune diseases. EAE is a paralytic and inflammatory disease of the central nervous system and in many respects resembles the pathology of the most common human demyelinating disease, multiple sclerosis (MS). Recent development in the analysis of the T cell receptor (TCR) at the molecular level has revealed that clones of autoreactive T cells only express a restrict number of the available T cell receptor specificities. This raises the hope that perhaps modulation of certain autoimmune diseases can be achieved through manipulation of the TCR itself. However, in the murine model, the analysis has so far been made only in three strains or strictly speaking, in two haplotypes because two of the three strains carry identical major histocompatibility complex genes and recognize the same myelin basic protein (MBP) T cell epitope. In rat, only the Lewis strain has been analysed in detail. Human study is still rather preliminary. To generalize the concept of limited heterogeneity in TCR gene usage by autoreactive T cells, this study will analyse the TCR specificities of two genetically diverse strains of mice, C57BI/6 and BALB/C. These two strains are unique in that induction of EAE by adoptive transfer fail to generate signs of disease in the recipient mice. EAE is induced only after the recipients are challenged at a later stage with MBP. The investigation of the nature of the TCR genes expressed in these "relatively resistant" strains will be of value to correlate immune mechanisms with TCR gene usage. To this end, MBP-specific T cell clones from B6 and BALB/C will be generated. Clones will be tested for encephalitogenicity and the MBP epitope they recognize. Cell surface expresion of TCR gene products will be monitored with specific monoclonal antibodies. At the molecular level, DNA probes specific for known V-region genes will be used to quantify RNA expression in encephalitogenic clones. Such analysis will also provide information regarding the prevalence of a specific V-region gene, V-beta- 8.2, in disease expression. Since B6 recipient mice do not develop disease until after challenged with MBP, this provides an ideal system to study the in vivo trafficking patterns of the transferred cells in relation to their "relative resistance" in EAE induction. By using the expression of the Thy-1 genetic marker, the presence of donor cells can be traced in various tissues of the recipient, especially in the brain and spinal cord. Taken together, these studies will provide a better appreciation of the underlying mechanisms of EAE and of MS.